Sanding device for lacquered surfaces



Jan. 14, 1969 L. .1. LUCAS 3,421,263

SANDING DEVICE FOR LACQUERED SURFACES Filed Sept. 21, 1964 Sheet of 4 Jan. 14, 1969 Y L. J. LUCAS SANDING DEVICE FOR LACQUERED SURFACES Sheet Filed Sept. 21, 1964 wuh FIG.5

L. J. LUCAS SANDING DEVICE FOR LACQUERED SURFACES Jam 14, 1969 J of 4 Sheet Filed Sept. 21, 1964 FIG. 6

Ill/1.

Jan. 14, 1969 L. J. LUCAS 3,421,263

Filed Sept. 21, 1964 Sheet v4 of 4 A' FIG. 10

United States Patent 3,421,263 SANDING DEVICE FOR LACQUERED SURFACES Lothar Johannes Lucas, Werdau, Germany, assignor to Joachim Kurt Lucas, Scarborough, Ontario, Canada Filed Sept. 21, 1%4, Ser. No. 398,837 US. Cl. 51-57 14 Claims Int. Cl. B24b 7/00 ABSTRACT OF THE DISCLOSURE A device for polishing, sanding or grinding a body surface in which a polishing head is pivotally connected with a pair of pivotally engaged arms each reciprocated independently by at least one eccentric to produce a randomly oriented pattern of movement of the polishing head.

This invention relates to means for the mechanical surface treatment of comparatively large surface areas, whereby these areas are smooth and polished.

It is conventional practice to employ manual labor in the polishing of comparatively large irregular surfaces such as painted vehicle bodies. As in aid in reducing the time required to polish these surfaces various types of hand held sanders and grinders have been employed.

It is also well known to have so called swing grinding machines for rotating grinding heads which help to ease the grinding and polishing of large surfaces, these conventional systems normally being driven by electrical or compressed air means, the devices held by hand to pass over the work. It will be apparent that such devices and the finish obtained is largely dependent upon the skill of the operator.

Accordingly, it is an object of the present invention to provide a polishing device whereby the required grinding and polishing of large surfaces is considerably simplified, the polishing action being similar to the motion normally used in manual polishing of such surfaces.

Mechanization of the grinding or polishing operation is attained through use of the device having preferably electrical drive means in which a movable grinding head having movable grinding bodies thereon is moved in a random pattern over the work surface, thereby to duplicate hand polishing methods.

The grinding action is accomplished by a pair of arms secured to crank means at one end and meeting at a common attachment point where the grinding head is attached. By suitable revolutions of the crank means at the end of the arm the individual polishing grains are caused to move in a random pattern, whereby the curved line followed by a particular grinding grain varies with each revolution of the crank, thereby to ensure that each grinding grain follows a different course as the grinding head is reciprocated.

In the case where extremely large work widths are to be polished the grinding heads can be connected in tandem thereby to increase the effective width of the polishing action.

In the treatment of large vehicle bodies such as cars and buses it is preferable to provide separate means for moving the vehicle beneath the polishing head this being done by suitably placing the vehicle on a moving track, the movement of which can suitably be controlled. It will be understood that various means for providing this movement to polish various surfaces can be utilized and it is not the intention of this invention to define any particular type.

In one form of the invention a separate transport device is provided which contains the vehicle body located thereice on, this moving device moving slowly forward in order to present a new surface to the polishing head at each stroke thereof. Upon completion of one pass of the vehicle beneath the grinding head the process is reversed until sufiicient polishing action has occurred.

Other objects and features of the invention Will be apparent from the following detailed descripition and accompanying drawings in which like numerals refer to like parts throughout the various views.

In the drawings:

FIG. 1 is a diagrammatic view of a preferred embodiment of the invention;

FIG. 2 is a similar diagrammatic view showing an arrangement for a comparatively small work Width;

FIG. 3 shows the arrangement of a pair of grinding heads connected in tandem;

FIG. 4 is a plan view of a grinding head according to the present invention;

FIG. 5 is a section along the line 55 of FIG. 4;

FIG. 6 is a side elevation of one crank means utilized with the present invention;

FIG. 7 is a front elevation of the device as shown in FIG. 6;

FIG. 8, as located on the next sheet, is a part sectional view of a crank mechanism used with a different portion of the invention;

FIG. 9 is a part sectional view of the attachment between the pair of arms used with the device; and

FIG. 10 is a representation of the trace made by a particle situated on the grinding head as shown in FIG. 4.

Having reference to FIG. 1 a diagrammatic representation of the invention is illustrated wherein a polishing head 11 is supported on a pair of arms 12 and 13. The extreme ends as at 14 and 15 of the arms 12 and 13 are secured to crank mechanisms.

The crank mechanism as at 15 comprises a crank 16 rotatably supported on the pivot point 17. The pivot point 17 is fixed in relation to a Work piece and suitable means are provided for rotating the crank 16 whereby the point 18 follows a circular path to reciprocate the polishing head 11.

The crank mechanism as at 19 comprises a stationary pulley 20 having a crank arm 21 rotatably mounted thereabout. A small pulley 22 is rotatably mounted on the extreme end as at 23 of the crank 21 and is rotated by the belt 24 passing therearound and around the large pulley 20. A second crank arm 25 is rigidly secured to the small pulley 22 whereby the crank arm 25 is rotated therewith the point 26 thus assuming a circular orbit about the point 23 and at the same time revolving about the point 27.

With reference to FIG. 2 a similar device is shown wherein the head 11 is mounted on the arms 28 and 29. A first crank at 30 rotates about the fixed point 31 whereby the point 32 assumes a circuit orbit. The crank 33 is rotatably fixed at the point 34 and rotates thereabout whereby the point 35 assumes a circular orbit. Thus by both cranks 30 and 33 rotating, the ends of the arms 28 and 29 are reciprocated whereby the polishing head .11 is caused to reciprocate in two directions.

With reference to FIG. 3 a further embodiment of the invention is shown which is similar to the device as illustrated in FIG. 2 but has the addition of a second polish ing head as at 36. An additional arm 37 is provided to space the heads 11 and 36 apart and the arm 38 is secured to the point 39 on the end of the crank 40, the crank 40 being rotatably pivoted at 41. By resort to this method a considerably large work area can be covered at any one time.

With reference to FIG. 4 a polishing head is indicated generally as 42 and comprises a frame 43 having three polishing discs 44, 45, and 46 secured thereto. Each polishing disc is secured by means of the ball joint as at 47 in FIG. and a central stem 48 is provided with a ball joint as at 49 whereby the frame 43 is movable rela tive to the stem 48.

It is preferable to form a slightly concave undersurface as at 50 on each pad 45 which facilitates adapting the device to curved surfaces. During normal use a polishing or grinding pad 51 is fitted to the undersurface of each pad 44, 45' and 46, these being replaceable upon becommg worn.

With reference to FIG. 6 and FIG. 7 a means for providing one reciprocating movement of the support arms is shown. From the drawings it will be seen that a driven pulley 52 is rotatably mounted in the bearing 53 on the frame 54. An arm 55 is secured to the pulley 52 by means of the shaft 56 and extends outwardly in rotatable contact with the stub shaft 57. The stub shaft 57 rotatably mounted in the bearing 58 supports an arm 59 by means of the pin as at 60, whereby the arm 59 is free to move in a vertical direction about the pin 60.

A raising and lowering device comprises the rotatable shaft 61 supporting the frame as at 62 which is adapted to support the arm 59 and still allow free movement thereof from side to side as the crank 55 rotates. It is preferable to provide a hydraulic cylinder 63 connected by means of the arm 64 to the shaft 61 for the operation thereof in order to raise and lower the frame 62. As a means for tensioning the downward position of the arm 59 a spring 65 is adjustably held by means of the nut and eye bolt arrangement as at 66. It is also preferable to provide the counter balancing spring 67 secured to the arm 68 whereby any free play in the shaft 61 is absorbed.

With reference to FIG. 8 as shown on the next sheet of drawings, a means for obtaining the double reciprocating motion as shown in FIG. 1 is illustrated. In this drawing a stationary pulley 69 is supported on the frame 70. A shaft 71 is rotatably mounted centrally through the pulley 69 and projects therebelow into rigid contact with a crank arm 72. The crank arm 72 is driven through the shaft 71 by means of the pulley 73, the drive means for the pulley not being shown.

The arm 72 supports a shaft 74 rotatably therein, shaft 74 being driven by means of the small pulley 75 operably connected to the large pulley 69 by means of the belt 76. A second crank arm 77 is secured at the lower end of the shaft 74 and supports a stub shaft 78 rotatably thereon. An arm 79 is pivotally supported at 80 in a manner similar to the arm 59 as shown in FIG. 6. As before it is preferable to provide a downward bias force by means of the spring 81 adjustably secured at 82.

Upon rotation of the pulley 73 by suitable means the crank arm 72 will pivot about the shaft 71 and the pulley 75 riding in the belt 76 will cause the smaller crank shaft 77 to rotate thereabout. Thus during rotation of the device the arm 79 will reciprocate in two directions and follow a double circular path as the point 30 rotates about the shaft 74 and revolves about the shaft 7.1.

With reference to FIG. 9 a means for securing both the arms 79 and 59 is shown wherein the stem 48 as shown in FIG. 5 is pivotally supported by means of the ball joint as at 83 and the arm 79 is secured as at 84. Thus during reciprocal movement of the arm 59 and 79 the ball joint at 83 allows the stem 48 to assume the required position.

With reference to FIG. a trace of a particle mounted on one of the pads as shown in FIG. 4 is shown. From this it will be seen that the path 85 as illustrated has a reciprocal pattern and overlaps in many directions and positions, without actually retracing an identical course.

In use it will be seen that the present invention can be utilized for pivoting a polished or ground surface on large irregular surfaces and that it is adaptable for various types and configurations of surfaces. By suitably mounting the device over a surface to be prepared and moving the surface beneath the polishing head a high degree of uniform grinding or polishing is obtained. It will be understood that although a preferred method is to move the work surface beneath the device the device can also be moved relative to the work surface in order that a certain area can be traversed.

As a specific example a device according to the diagram in FIG. 1 was constructed where the crank arm as at 16 was given a relative rotational speed of two hundred, and the crank arm 21 was given a relative rotational speed of seventy. The trace produced by such an arrangement is as shown in FIG. 10 and it will be seen that the single spot traces a regular pattern which produces a random polishing and thus an even fiat surface.

It will be seen that since the rotation of crank 16 relative to crank 26 is constant then each portion of rotation of crank 21 will produce a different position for the head 11. Thus a great degree of surface cover is obtained with the polishing device. Further to this, due to natural irregularities in the polishing pads secured to the bottom of the polishing head 42 as shown in FIG. 4 and FIG. 5 there is a slight tendency for these pads to creep whereby the surface cover is increased.

It will be further understood that although specific embodiments of the invention have herein been described, the invention also contemplates such variations as may fall within the scope of the appended claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A polishing device for polishing and grinding irregular surfaces and comprising: a pair of arms pivotally engaged about a common axis; a polishing head pivotally supported at said common axis; a crank arm rotatably secured to each of the free ends of said pair of arms; and means for independently rotating each of said crank arms, whereby upon said crank arms rotating said head is caused to move in a randomly oriented pattern over said surfaces, thereby to grind and polish same.

2. A polishing device for polishing and grinding irregular surfaces and comprising: a pair of arms pivotally engaged about a common axis; a frame pivotally secured to said common axis; at least two polishing pads pivotally secured to said frame; a crank arm rotatably secured to each of the free ends of said pair of arms; and means for independently rotating each of said crank arms, whereby upon said crank arms rotating said head is caused to move in a randomly oriented pattern over said surfaces, thereby to grind and polish same.

3. A polishing device for polishing and grinding irregular surfaces and comprising: a pair of arms pivotally engaged about a common axis; a polishing head pivotally supported at said common axis; a first crank arm secured to one said pair of arms at the free end thereof; a large pulley mounted stationary; a large crank arm rotatably supported centrally through said large pulley; a small pulley rotatably supported on the free end of said large crank arm; belt means operably connecting both said pulleys; and a small crank arm secured to said small pulley and rotatable therewith, the remaining one of said pair of arms pivotally secured to said small crank arm, whereby upon rotation of said large crank arm said small pulley is caused to revolve about said large pulley by means of said belt means, said small pulley also being rotated thereby to rotate said small crank thus to reciprocate said head, said first crank arm also causing said head to reciprocate to produce a polishing pattern.

4. A polishing device for polishing and grinding irregular surfaces and comprising: a pair of arms pivotally engaged about a common axis; a frame pivotally secured to said common axis; at least two polishing pads pivotally secured to said frame; a first crank arm secured to one said pair of arms at the free end thereof; a large pulley mounted stationary; a large crank arm rotatably supported centrally through said large pulley; a small pulley rotatably supported on the free end of said large crank arm; belt means operably connecting both said pulleys; and a small crank arm secured to said small pulley and rotatable therewith, the remaining one of said pair of arms pivotally secured to said small crank arm, whereby upon rotation of said large crank arm said small pulley is caused to revolve about said large pulley by means of said belt means, said small pulley also being rotated thereby to rotate said small crank thus to reciprocate said head, said first crank arm also causing said head to reciprocate to produce a polishing pattern.

5. A device for polishing, sanding or grinding a body surface, comprising: a pair of arms pivotally connected about a common axis; polishing means pivotally connected with said arms at said common axis; and means for moving independently about at least one locus each of said arms at a point remote from said common axis, whereby said arms are reciprocable and said polishing means is movable in a randomly oriented pattern over said surface.

6. A device as claimed in claim 5 in which at least one of said loci is itself movable about a further locus.

7. A device as claimed in claim 5 in which the means to move at least one of said arms comprises rotatable eccentric means.

8. A device as claimed in claim 5 in which the means to move at least one of said arms comprises eccentric means rotatable about a first locus, said first locus being rotatable by further eccentric means about a second locus.

9. A device as claimed in claim 5 in which one of said arms carries a stem comprising said common axis, the other of said arms being connected with said stem by a ball joint.

10. A device as claimed in claim 9 in which said polishing means is connected at one end of said stem by a universal joint.

11. A device as claimed in claim 5 in which said means for moving each of said arms comprising a crank arm pivotally connected thereto at said point and means for rotating each crank arm.

12. A device as claimed in claim 5 in which one of said arms comprises a cantilever frame having a pair of elongated members pivotally connected one with another in spaced relationship by a cross-member, the free end of the other of said arms being pivotally connected with said cross-member at a point intermediate the members pivotally connected thereto, polishing means mounted at each pivotal connection of the cross-member with the elongated members, and means to rotate the free ends of said arm and said elongated members each about a separate locus.

13. A device for polishing, sanding or grinding a body surface, comprising: a pair of cantilever arms each vertically pivotable at one end and pivotally connected about a common axis at their other ends; a polishing head universally connected with said arms at said common axis; a pair of crank arms one pivotally connected to, and adapted to rotate, the vertically pivoted end of each of said arms independently in a horizontal plane; and means to rotate said crank arms, whereby said arms are reciprocable and head is movable in a randomly oriented pattern over said surface.

14. A device as claimed in claim 13 in which at least one of said crank arms is rotatably mounted on a further crank arm, and means to rotate said one crank arm at a speed proportional to said further crank arm.

References Cited UNITED STATES PATENTS 253,086 1/1882 Morris 51-68 FOREIGN PATENTS 1,470 1857 Great Britain. 410,037 2/ 1925 Germany.

DONALD R. SCHRAN, Primary Examiner. 

